Pokémon

Related species

Nidoran

The Nidoran family is a special case in terms of gender. Introduced in Generation I, before gender was known for all Pokémon, Nidoran♀ and Nidoran♂ are considered separate species of Pokémon and indeed have many differences, from appearance to moveset. However, Nidoran♀ and Nidoran♂ Eggs have a 50/50 chance of hatching into either Nidoran♀ or Nidoran♂, confirming that they are related.

Other

In a manner similar to Nidoran, Eggs produced by Illumise may hatch into Volbeat. While Latias and Latios are in the Undiscovered Group in the games, likely due to being legendary Pokémon, Latias have produced Eggs containing Latios in the anime, confirming that they are related. Mothim and Wormadam evolve from male- and female-gendered members of the same species.

Gender differences

Generation IV premiered minimal differences in sprite between two Pokémon of the same species. For example, a male Raichu will have the full tail seen in previous games, while the female is missing the very tip of it.

Gender-based evolution

Some Pokémon evolutions can only be obtained if they are of a certain gender:

Trivia

In Generation II, a Pokémon's gender was determined through its Attack IV. Due to this, unless a Pokémon was a member of an all-female species, such as Nidoran♀ and Smoochum, it could never have a maximized Attack stat, as female Pokémon were given the lower half of the IV range. This also caused the inability for a female Pokémon of a species with a gender ratio of seven males to one female—like the starter Pokémon and Eevee—to be Shiny, due to that also running partly off of the Attack IV. In Generation III this was addressed, with IVs no longer determining either of these, allowing for Pokémon species with two genders to have females with maximized Attack and simultaneously retain its chances of being Shiny.

Although its English and French names suggest that it is exclusively male, Mr. Mime may be of either gender. This is due to the fact that it was given its name prior to the introduction of gender to the series.

There are other Pokémon that have a similar scenario to Mr. Mime. For example, the names of Seaking, Kingler, and Slaking suggests that they are exclusively male due to the King in their name. However, they can be of either gender.

Similarly, Gardevoir and Glalie can be either gender, even though each has a single-gender counterpart

Since Azurill has a different gender ratio than Marill and Azumarill, one in three female Azurill will be male after evolving into Marill, dependent on the personality value of the Azurill in question.

In the international versions of Generation II, due to how the battlefield display is programmed, Nidoran♂ and Nidoran♀ have their gender icon shown twice, once in their name, and once after the level. This does not occur in the Japanese and Korean games, however, as the gender icon was present after all Pokémon's names due to the shorter character limit there. This was addressed in all later generations, which prevent the gender icon from showing up when an un-nicknamed Nidoran of either gender is on the field.